1. Field of the Invention
This invention relates generally to mechanical fasteners, and specifically to an easily releasable slide action latch that can be applied to discreet objects to achieve disconnectable retention.
2. Description of the Prior Art
Mechanical latches represent a method of releasably engaging and holding or otherwise joining or assembling objects such as panels, enclosures, belts, fabric, or other similar, discreet objects. A wide variety of special-purpose fasteners are currently employed in the industry for quick-operating, repeated access applications.
As a specific example, to which no limitation is intended, currently in use for fastening chin-straps on to football helmets is a snap-ring, button type fastener. This widely used conventional fastener is fixed to a chin-strap by being threaded through two parallel slots on a rectangular frame and then typically contains a cylindrical grooved insert that's been riveted to a side of the rectangular frame. The grooved insert houses a retaining ring that is used to clasp the head of a peg or bolt previously fixed to the side of the helmet. Helmet chin-straps are first snapped on to one side of the helmet, passed along the jaw where it cups the wearer's chin, and then snapped on to the other side of the helmet. Typically constructed of heavy fabric, the straps will not tear or separate, even when subjected to high tensile loads.
While the simplicity of a snap-ring fastener design for chin-straps lends itself well to quick-application and release, it also tends to inadvertently "pop" open during high-impact collisions, a common occurrence in football. The snap-ring mechanism does not isolate external forces frequently generated by either a pull on the helmet chin-strap, or a direct or near impact to the snap-ring section. A tug on the loose end of the strap by another player's hand or arm, or a collision along the side of the helmet, can easily generate enough force to disengage the retention ring from the head of the peg. An unsecured helmet can then swivel uncontrollably about the wearer's head, creating a serious safety risk. Additionally, the head-on collisions common in American football, continuously generate impact forces within the face-guard bars fixed to the front face of a helmet. On a secure helmet, these impact forces are transferred to the shell of the helmet, and are ultimately absorbed by the player's head and neck, through a pull reaction produced by a properly fastened chin-strap. The front rim of the helmet, swiveling down and smacking the bridge of the nose, after a direct face-guard collision, is a painful, all too frequent consequence of a football helmet whose chin-strap fastener has inadvertently popped open. Evidence to the certainty of this problem can be seen by noting a centrally located rubber bumper along the front face of a majority of helmet's, representing an effort by manufacturer's to attenuate this common nose injury. Further evidence to the questionable reliability of a button type, snap-ring fastener mechanism, is noted by the prevalent trend toward use of helmet's containing double fasteners on each side, and frequent witnessing of a completely loose helmet rolling along the playing field after a particular aggressive scrimmage play.
Downey, under U.S. Pat. No. 4,559,679 (1985), attempts to introduce a more secure helmet strap fastener system. The reference patent discloses a complex to manufacture helmet fastener, whose disengagement consists of simultaneous, inwardly directed pressure into two opposing transverse openings of a unitary body member. This unitary body member, critical for operation, is not permanently secured to any other component, and could easily be removed from the scene. Manufacture of this unitary body member using conventional injection molding techniques would be very difficult, due to an arrangement requiring longitudinal and transverse openings in conjunction with flexible side latches. Designing deflection behavior for the first latching member so that it remains securely retained in the unitary body member, while a second latching member properly engages it, also poses significant engineering challenges.
Other alternative fasteners are depicted in U.S. Pat. Nos. 4,150,464 (1979), 4,809,409 (1989) and 684,497. Tracey, under U.S. Pat. No. 4,150,464 (1979), defines a buckle using a pair of opposing transverse locking slots in a system very similar to Downey. Release of the buckle also requires simultaneous inwardly directed pressure into two opposing transverse openings. Davies, under U.S. Pat. No. 684,497 (1901), illustrates a fastener using dual spring actuated hooks which engage internal projections on a stationary socket. Release of this system requires a similar, simultaneous inwardly directed lateral pressure along sides of the fasteners legs in order to compress a centrally placed spring. Van Riesen, under U.S. Pat. No. 4,809,409 (1989), describes a belt lock requiring a minimum of six pieces, containing a readily exposed transverse release mechanism. The plunger releasable latch fastener of this invention introduces a system requiring only one singular, simple yet reliable, longitudinal, in-line release action. Prior Art on a variety of quick-operating fasteners is referenced in Basics Design Engineering, Machine Design magazine, June 1991, pgs. 1075-1089. While obvious to those skilled in the art that some of the more rugged, complex latching mechanisms commonly available in the industry will withstand heavy impact applications, they are generally much more difficult to fasten and release.
In summary, review of Quick-Operating Mechanical fasteners heretofore known as prior art, does not readily disclose a system having combined attributes of:
a--reliable, high-impact mechanical shock resistance, PA0 b--design for simplicity of manufacture, and PA0 c--extreme ease of application and removal, PA0 a--To provide a disconnectable closure which requires only a simple, singular, unidirectional application of force to disengage. PA0 b--To provide a disconnectable closure which requires only one flexing spring member. PA0 c--To provide a disconnectable closure which requires a minimum of parts, and is of a design facilitating inexpensive manufacture. PA0 d--To provide a disconnectable closure which reliably resists intense, direct mechanical impact. PA0 e--To provide a disconnectable closure which can, within context of a specific embodiment, be applied to conventional football helmets without requiring any additional modification, due to being footprint compatible with snap-ring, button type fasteners in current use.
in a manner that improves upon the noted limitations of button-type, snap-ring fasteners. Securing a chin-strap to a football helmet, being a specific example wherein one such type fastener is currently employed and noticeably found wanting.